Normally, when the volume is migrated between different volume managers, data copy is carried out by reading out, by the volume manager of the migration source, data in a data area from a disk of the migration source, and writing, by the volume manager of the migration destination, the read data into a disk of the migration destination.
In addition, when functions of the volume manager of the migration source are completely open to the public, the migration is carried out at high speed by rewriting only a header area of the header area and the data area, which are stored in the disk, as long as the volume manager of the migration destination supports equivalent or more functions.
Incidentally, for example, U.S. Pat. No. 5,983,317 discloses a technique for enabling data sharing between the mainframe and the open system. Specifically, a disk control apparatus is connected with a CPU the UNIX (Registered Trade Mark) operating system controls via the SCSI interface, and is connected with a CPU the VOS3 operating system controls via the channel interface. In the CPU, the CKD record access library and the VSAM access library exist, and the CPU accesses the VSAM record stored in the CKD format into the disk control apparatus, in the FBA format, and can access an application program of the CPU as the VSAM record based on the VSAM control information. This publication discusses data sharing between different operation systems, and does not discuss the complete migration of the volume manager.
However, because the volume size of the volume to be migrated is rapidly increased, recently, the initially described method of coping the data area requires a huge time for the volume migration. Therefore, there are many cases where the method cannot be actually carried out.
In addition, when the volume manager of the migration source supports a technique such as an alternating block (other block mapped when a block defect occurs in the primary data storage location) and this specification is not completely open to the public, the volume manager of the migration destination cannot map an appropriate block at a pertinent offset of the logical volume.